Virtual image display device and optical unit

Abstract

This reduces unwanted light in an optical system that does not generate intermediate images and does not have an optical aperture. [Solution] The direct virtual image display device comprises a first prism into which image light from a display element is incident, a second prism joined to the first prism to form a prism light guide member, a semi-transparent reflective film provided at the joint between the first prism and the second prism and reflecting the image light guided in the first prism, a first lens positioned opposite the outer surface of the first prism into which the image light reflected by the semi-transparent reflective film is incident, a transmissive mirror formed on the first lens and reflecting a portion of the image light reflected by the semi-transparent reflective film toward the semi-transparent reflective film, and a quarter-wave plate positioned between the outer surface of the first prism and the first lens, wherein the third surface in contact with the first surface into which image light from the display element is incident and the second surface opposite the first lens is inclined with respect to a virtual first plane perpendicular to the first direction in which the wearer's eyes are aligned.

Description

Technical Field

[0001] The present invention relates to a see-through type virtual image display device and an optical unit that enable observation of a virtual image.

Background Art

[0002] There is known a head-mounted display device including an image display device, a concave mirror, and a semi-transmissive element, and an optical system for projecting an image formed by the image display device onto a user's retina through the semi-transmissive element, the concave mirror, the semi-transmissive element, and the exit pupil of the device in sequence, wherein the head-mounted display device is provided with a first lens disposed between the image display device and the semi-transmissive element and collimating light generated by the image display device to the optical system (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described head-mounted display device, since no intermediate image is generated and there is no optical aperture, unnecessary light such as ghosts and stray light that is unnecessary for image display is confined inside the optical system and reaches the eyes.

Means for Solving the Problems

[0005] One aspect of the present invention is a virtual image display device of the direct virtual image type, comprising: a display element that emits image light; a first prism into which the image light from the display element is incident; a second prism joined to the first prism to form a parallel plate-shaped prism light guide member; a semi-transparent reflective film provided at the joint between the first prism and the second prism and reflecting the image light guided in the first prism; a plano-convex first lens positioned opposite the outer surface of the first prism into which the image light reflected by the semi-transparent reflective film is incident; and a reflective film formed on the convex surface of the first lens and reflected by the semi-transparent reflective film. The prism light guide member comprises a transmissive mirror that reflects a portion of the projected image light toward a semi-transparent reflective film, and a quarter-wave plate positioned between the outer surface of the first prism and the first lens with an air gap in between. The third surface of the prism light guide member, which is in contact with the first surface onto which the image light from the display element is incident and the second surface facing the first lens, is inclined at a certain angle with respect to a virtual first plane perpendicular to the first direction in which the eyes of the wearer wearing the virtual image display device are aligned, in a direction in which the prism light guide member tapers as it moves from the wearer's eyes toward the first lens along the optical axis of the first lens.

[0006] An optical unit in one aspect of the present invention is a direct virtual image type optical unit comprising: a display element that emits image light; a first prism into which the image light from the display element is incident; a second prism joined to the first prism to form a parallel plate-shaped prism light guide member; a semi-transparent reflective film provided at the joint between the first prism and the second prism and reflecting the image light guided in the first prism; a plano-convex first lens positioned opposite the outer surface of the first prism into which the image light reflected by the semi-transparent reflective film is incident; and a reflective film formed on the convex surface of the first lens and reflected by the semi-transparent reflective film. The optical unit comprises a transmissive mirror that reflects a portion of the projected image light toward a semi-transparent reflective film, and a quarter-wave plate positioned between the outer surface of the first prism and the first lens with an air gap in between. The third surface of the prism light guide member, which is in contact with the first surface onto which the image light from the display element is incident and the second surface facing the first lens, is inclined at a certain angle with respect to a virtual first plane perpendicular to the first direction in which the eyes of the wearer wearing the optical unit are aligned, in a direction in which the prism light guide member tapers as it moves from the wearer's eyes toward the first lens along the optical axis of the first lens. [Brief explanation of the drawing]

[0007] [Figure 1] This is an external view illustrating the usage state of the virtual image display device of the first embodiment. [Figure 2] This is a lateral cross-sectional view illustrating the internal structure of one of the display devices. [Figure 3] This is a conceptual perspective view of a virtual image display device using related technologies. [Figure 4] This is a conceptual cross-sectional view of a virtual image display device using related technologies. [Figure 5] This is a conceptual perspective view of the virtual image display device of the first embodiment. [Figure 6] This is a conceptual cross-sectional view of a virtual image display device according to the first embodiment. [Figure 7] This figure shows the luminance distribution of image light and unwanted light observed by the eye when using a virtual image display device based on related technologies. [Figure 8] This figure shows the luminance distribution of image light and unwanted light observed by the eye when using a virtual image display device based on related technologies. [Figure 9] This figure shows the luminance distribution of image light and unwanted light observed by the eye when using a virtual image display device based on related technologies. [Figure 10] This figure shows the luminance distribution of image light and unwanted light observed by the eye when using the virtual image display device of the first embodiment. [Figure 11] This figure shows the luminance distribution of image light and unwanted light observed by the eye when using the virtual image display device of the first embodiment. [Figure 12] This figure shows the luminance distribution of image light and unwanted light observed by the eye when using the virtual image display device of the first embodiment. [Figure 13] This is a conceptual perspective view of a virtual image display device according to a second embodiment. [Figure 14] This is a conceptual cross-sectional view of a virtual image display device according to a second embodiment. [Modes for carrying out the invention]

[0008] [First Embodiment] A first embodiment of the virtual image display device, etc., according to the present invention will be described below with reference to Figures 1 and 2, etc.

[0009] Figure 1 illustrates the wearing state of a head-mounted virtual image display device (hereinafter also referred to as a head-mounted display or HMD) 200. The HMD 200 causes the observer or wearer US to perceive an image as a virtual image. In Figure 1, etc., X, Y, and Z are Cartesian coordinate systems. The +X direction corresponds to the lateral direction where the eyes (EY) of the observer or wearer US wearing the HMD 200 are aligned. The +Y direction corresponds to the upward direction perpendicular to the lateral direction where the eyes (EY) of the wearer US are aligned. The +Z direction corresponds to the forward or frontal direction for the wearer US. The ±Y directions are parallel to the vertical axis or the vertical direction.

[0010] The HMD200 comprises a first virtual image display device 100A for the right eye and of the direct virtual image type, a second virtual image display device 100B for the left eye and of the direct virtual image type, a pair of temple-shaped support devices 100C that support these virtual image display devices 100A and 100B, and a user terminal 90 which is an information terminal. The first virtual image display device 100A functions as an HMD on its own and consists of a first display drive unit 102a located at the top and a first combiner 103a that is spectacle-lens-shaped and covers the area in front of the eyes. Similarly, the second virtual image display device 100B also functions as an HMD on its own and consists of a second display drive unit 102b located at the top and a second combiner 103b that is spectacle-lens-shaped and covers the area in front of the eyes. The support device 100C is a mounting member that is attached to the head of the wearer US and supports the upper ends of the pair of combiners 103a and 103b via the display drive units 102a and 102b, which are integrated in appearance. The first virtual image display device 100A and the second virtual image display device 100B are optically identical or horizontally inverted versions thereof, and a detailed explanation of the second virtual image display device 100B will be omitted.

[0011] Figure 2 is a side cross-sectional view illustrating the internal structure of the first virtual image display device 100A. The first virtual image display device 100A comprises a first image forming element 11a, a first display unit 20a, and a first circuit member 80a. The first image forming element 11a is also called the display element 11. The first display unit 20a is an imaging optical system IS that directly forms a virtual image without forming an intermediate image, and is also called a direct virtual image optical system DIS. The imaging optical system IS has a first lens 30, a first flat plate member 40, and a second flat plate member 50. The first lens 30 functions as protective glass that protects the display surface 11d of the display element 11. The first flat plate member 40 has a third lens 44 facing the first lens 30. The first flat plate member 40 guides the image light ML emitted from the display element 11 and incident from the third lens 44 to the second lens 53 of the second flat plate member 50. The second flat plate member 50 partially returns the image light ML from the first flat plate member 40 to the first flat plate member 40, reflecting it toward the pupil position PP or eye EY, and also causes the ambient light OL to be incident on the pupil position PP via the first flat plate member 40. The first lens 30, the third lens 44, the first flat plate member 40, and the second flat plate member 50 each function as lenses having positive refractive power.

[0012] Although a detailed explanation is omitted, the second virtual image display device 100B comprises a second image forming element 11b, a second display unit 20b, and a second circuit member 80b. The second image forming element 11b is the same as the first image forming element 11a, the second display unit 20b is the same as the first display unit 20a, and the second circuit member 80b is the same as the first circuit member 80a.

[0013] In the first virtual image display device 100A, the first image forming element 11a is a self-luminous type image light generating device. The first image forming element 11a emits video light ML to the first flat plate member 40 through the first lens 30. The first image forming element 11a is housed and supported in the case 71. The first image forming element 11a is, for example, an organic EL (organic electroluminescence) display, and forms a color still image or moving image on the two-dimensional display surface 11d. The first image forming element 11a is driven by the first circuit member 80a to perform a display operation. The first image forming element 11a is not limited to an organic EL display, and can be replaced with a display device using inorganic EL, organic LED, LED array, laser array, quantum dot light emitting type element, etc. The first image forming element 11a is not limited to a self-luminous type image light generating device, and may be composed of an LCD or other light modulation element, and an image may be formed by illuminating the light modulation element with a light source such as a backlight. As the first image forming element 11a, instead of an LCD, LCOS (Liquid crystal on silicon, LCoS is a registered trademark), a digital micro mirror device, etc. can also be used. In the first virtual image display device 100A, the optical device excluding the first circuit member 80a is called an optical unit 100. The optical unit 100 includes a direct virtual image type optical system, and can also be said to be a part corresponding to the direct virtual image optical system DIS that constitutes the first virtual image display device 100A.

[0014] The first display unit 20a includes a first lens 30, a first flat plate member 40, a polarization separation film 45A as a semi-transmissive reflection film 45, and a second flat plate member 50. In the first display unit 20a, the first lens 30 has a positive refractive power, and image light ML from the first image forming element 11a is incident thereon. The first lens 30 has a light incident surface 30f on a plane joined to the first image forming element 11a and a convex light emitting surface 30g. The light emitting surface 30g is, for example, spherical, but can be an aspherical surface having an axially symmetric shape. The first lens 30 can be considered as being divided into a parallel flat plate 31 and a lens portion 32. By ensuring that the thickness of the parallel flat plate 31 is a predetermined value or more, foreign matter adhering to the surface of the first lens 30 becomes less conspicuous. The lens portion 32 is a plano-convex lens having a positive refractive power. A plano-convex lens has one surface having a planar shape and the other surface having a convex shape. The first lens 30 is made of, for example, fused quartz and has a relatively low refractive index.

[0015] The first flat plate member 40 has a third lens 44 which is a plano-convex lens, a first prism 41 which is a parallel flat plate, and a second prism 42 which is a parallel flat plate. The third lens 44 and the first prism 41 are joined at inclined surfaces 44b and 41a. The first prism 41 and the second prism 42 are joined at inclined surfaces 41d and 42d. The combination of the third lens 44, the first prism 41, and the second prism 42 is called a prism light guide member 48. The prism light guide member 48 has the appearance of a parallel flat plate. A polarization separation film 45A as a planar semi-transmissive reflection film 45 is formed on an inclined surface 41d formed on the lower side of the first prism 41. The combination of the prism light guide member 48 and a second flat plate member 50 described later corresponds to the first combiner 103a in FIG. 1.

[0016] The third lens 44 is a plano-convex lens having a positive refractive index, and has an incident optical surface 44a facing the light emitting surface 30g of the first lens 30 and an inclined surface 44b coupled to the first prism 41. The incident optical surface 44a is convex and is, for example, spherical, but can be an axially symmetric aspherical surface. The third lens 44 is made of, for example, fused quartz and has a relatively low refractive index. The third lens 44 has the same refractive index as the first lens 30.

[0017] The first prism 41 has a bevel 41a connected to the bevel 44b of the third lens 44, an inner surface 41b, an outer surface 41c, and a bevel 41d. The first prism 41 further has a right side surface 41s and a left side surface 41m, which will be described later (see Figures 5 and 6). The first prism 41 has a rectangular prism shape with bevel 41a, inner surface 41b, outer surface 41c, and bevel 41d as its sides, and when viewed from the X-axis direction, it has a trapezoidal longitudinal cross-section in the YZ plane with the inner surface 41b and outer surface 41c as parallel bases. The first prism 41 guides the image light ML incident from the bevel 41a until it is reflected by the inner surface 41b, outer surface 41c, and bevel 41d and then exits from the outer surface 41c. Here, the inclined surface 41a is tilted downwards in the forward direction as a whole, and the optical axis passing through the inclined surface 41a extends in a direction between the forward +Z direction and the upward +Y direction. This makes it easier to position the first image forming element 11a, which is the display element 11, on the outside side of the inner surface 41b, and allows adjustment of the angle at which the image light ML propagates in the first prism 41 (inside or within the first prism 41). The inner surface 41b and the outer surface 41c are parallel to each other and extend perpendicular to the optical axis AX between them and the pupil position PP. The inner surface 41b and the outer surface 41c internally reflect the image light ML (i.e., reflect it on the inside of the object surface), and it is especially desirable that they perform total internal reflection. The inner surface 41b can be hard-coated to improve scratch resistance or abrasion resistance. The inclined surface 41d is a plane. The inclined surface 41d forms an acute angle with respect to the outer surface 41c, specifically an angle of 25° to 32°. The distance between the optical axis AX passing through the pupil position PP and the first lens 30 is approximately 20 mm. The first prism 41 is made of glass or resin material and has a refractive index higher than that of the first lens 30.

[0018] The number of reflections of the image light ML in the first prism 41 is basically once on the inner surface 41b, once on the outer surface 41c, and once more on the polarization separation film 45A, which will be described later. By making the number of internal reflections of the image light ML in the first prism 41 two, it is possible to increase the field of view of the image light ML, the pupil position PP, or its aperture PPa, while avoiding the mixing of light with different reflection counts within the first prism 41. The image light ML reflected by the inner surface 41b and the outer surface 41c does not form an intermediate image in the first display unit 20a or the imaging optical system IS, so the degree of divergence is suppressed compared to the initial divergence state when emitted from the first image forming element 11a, but it enters the inner surface 41b and the outer surface 41c in a diverged state and the divergence state is maintained. Here, the divergence state of the image light ML means a state in which the area occupied by the image light ML on an arbitrary virtual plane perpendicular to the optical axis gradually expands as the image light ML travels along the optical axis. Furthermore, the degree of divergence of the image light ML is suppressed to such an extent that, at least in any virtual plane perpendicular to the optical axis, the image light ML, including before and after reflection at the inner surface 41b and outer surface 41c, remains inside the first prism 41.

[0019] The second prism 42, like the first prism 41, has a rectangular prism shape and a trapezoidal longitudinal cross-section. More specifically, the second prism 42 has an inner surface 42b, an outer surface 42c, a beveled surface 42d, and a lower plane 42w, and has a rectangular prism shape with the inner surface 42b, outer surface 42c, beveled surface 42d, and lower plane 42w as its sides, and when viewed from the X-axis direction, it has a trapezoidal longitudinal cross-section in the YZ plane with the inner surface 42b and outer surface 42c as parallel bases. The second prism 42 further has a right side surface 42s and a left side surface 42m, which will be described later (see Figures 5 and 6). The second prism 42 transmits the image light ML incident from the beveled surface 42d and emits it from the inner surface 42b. The inner surface 42b and the outer surface 42c are parallel to each other and extend perpendicular to the optical axis AX between them and the pupil position PP. The inner surface 42b can be hard-coated to improve scratch resistance or abrasion resistance. The second prism 42 is made of glass or resin material and has a refractive index equal to that of the first prism 41.

[0020] The polarization separation film 45A is integrally formed on the bevel surface 41d of the first prism 41 and sandwiched between the bevel surface 41d of the first prism 41 and the bevel surface 42d of the second prism 42. The space between the polarization separation film 45A and the bevel surface 42d is filled with bonding adhesive CT. The polarization separation film 45A is formed of a dielectric multilayer film and efficiently reflects s-polarized s image light ML when the image light ML contains s-polarized s, and efficiently transmits p-polarized p image light ML when the image light ML contains p-polarized p. The polarization separation film 45A only needs to selectively reflect the image light ML according to its polarization direction, and may be, for example, a wire grid. The polarization separation film 45A only needs to have a flat surface that does not affect image formation. The polarization separation film 45A may also have a slightly curved surface that is convex or concave to the extent that it does not affect image formation. The scratch resistance or abrasion resistance of the polarization separation film 45A can be improved by applying a hard coat to its surface. Furthermore, the space between the polarization separation film 45A and the bevel surface 41d may be filled with a permeable filler instead of adhesive CT. In this case, the bond between the first prism 41 and the second prism 42 may be maintained by supporting them from the outside with a support member or the like. Also, the polarization separation film 45A may be integrally formed on the bevel surface 42d of the second prism 42 instead of the bevel surface 41d of the first prism 41.

[0021] The tilt angle θ of the polarization separation film 45A with respect to the XY plane is 90°-β0 or greater, where β0 is the reflection angle of the image light ML on the optical axis AX in the first prism 41. Assuming that the polarization separation film 45A does not obstruct the path of the image light ML, and assuming that βmax is the maximum reflection angle of the image light ML, it is desirable that the tilt angle θ of the polarization separation film 45A is smaller than βmax. The reflection angle β0 of the image light ML corresponds to the angle between the normal to the inner surface 41b and the optical axis AX passing through the incident optical surface 44a, and is an acute angle. In other words, the optical axis AX of the incident optical surface 44a extends in a direction less than 90° from the normal to the inner surface 41b.

[0022] The second flat plate member 50 has a thin quarter-wave plate 51 and a cover member 52. The quarter-wave plate 51 is a crystal or the like with an optical axis between the X and Y directions, and converts the s-polarized s image light ML reflected by the polarization separation film 45A into circularly polarized c, and converts the circularly polarized c image light ML reflected by the cover member 52 into p-polarized p. The quarter-wave plate 51 is positioned between the outer surface 41c of the first prism 41 and the second lens 53 with an air gap in between. The cover member 52 has a plano-convex second lens 53, a concave-flat compensating lens 54, a compensating plate 55 provided around the compensating lens 54 and extending parallel to the prism light guide member 48, and a transmission mirror 56.

[0023] The second flat plate-shaped member 50 is positioned approximately 20 μm to 50 μm away from the first flat plate-shaped member 40. The outer surfaces 41c and 42c of the first flat plate-shaped member 40 and the inner surface 50c of the second flat plate-shaped member 50 may be slightly curved, and a minute step may be formed at the boundary of the outer surfaces 41c and 42c. However, by setting the distance between the outer surfaces 41c and 42c and the inner surface 50c to 20 μm or more, more preferably 30 μm or more, it is possible to avoid these surfaces being excessively close together. Conversely, by setting the distance between the outer surfaces 41c and 42c and the inner surface 50c to 50 μm or less, it is possible to avoid an increase in the thickness of the first combiner 103a formed by combining the first flat plate-shaped member 40 and the second flat plate-shaped member 50. A spacer 61 is provided between the outer surfaces 41c, 42c of the first flat plate member 40 and the inner surface 50c of the second flat plate member 50 to adjust the distance between the first flat plate member 40 and the second flat plate member 50 and fix them in a relative position. The spacer 61 is not provided around the entire circumference of the second flat plate member 50. In other words, the gap SP between the first flat plate member 40 and the second flat plate member 50 is not sealed and is in communication with the outside world.

[0024] In the cover member 52, the second lens 53 is thin but has positive refractive power and has a flat surface 53f joined to the quarter-wave plate 51 and a convex surface 53g facing the compensating lens 54. The convex surface 53g is, for example, a sphere, but can be an axially symmetric aspherical surface. The compensating lens 54 is thin but has positive refractive power and has a concave surface 54f facing the second lens 53 and a flat surface 54g. The compensating plate 55 is a parallel plate and has a pair of flat surfaces 55f, 55g. Here, the concave surface 54f of the compensating plate 55 has the same shape as the convex surface 53g of the second lens 53. The flat surface 54g of the compensating lens 54 and the flat surface 55g of the compensating plate 55 are on the same plane and continuous. The transmission mirror 56 is a thin film formed on the convex surface 53g of the second lens 53 and has the same shape as the convex surface 53g. The combination of the second lens 53 and the transmissive mirror 56 is called the first light-gathering and reflecting section CR1.

[0025] The second lens 53, the compensating lens 54, and the compensating plate 55 are made of resin material. The second lens 53, the compensating lens 54, and the compensating plate 55 have the same refractive index. The refractive index of the second lens 53, etc., is lower than that of the first prism 41. The compensating lens 54 and the compensating plate 55 are optical elements 58 integrally formed from the same resin material.

[0026] The combination of the second lens 53, the compensating lens 54, and the compensating plate 55 functions as a parallel plate as a whole. In other words, ambient light OL incident at the positions of the compensating lens 54 and the compensating plate 55 passes through them without being affected by the lensing effect of the compensating lens 54, etc., or by the step present on the outer edge of the compensating lens 54. In this way, the compensating lens 54 optically compensates for the effect of the second lens 53 on ambient light OL. In this sense, the plane 53f of the second lens 53, the plane 54g of the compensating lens 54, and the planes 55f, 55g of the compensating plate 55 are not necessarily limited to strictly flat planes, but may be, for example, approximately flat, or may include curved surfaces partially or entirely. Furthermore, the plane 53f of the second lens 53, the plane 54g of the compensating lens 54, and the planes 55f, 55g of the compensating plate 55 may include curved surfaces for correcting the wearer's vision, or curved surfaces as a design element, such as sunglasses or fashion glasses, to the extent that it does not cause any inconvenience in terms of optical performance. The flat surfaces 54g and 55g of the compensating lens 54 and compensating plate 55 can be coated with an anti-reflective film or a hard coating. The ambient light OL that passes through the compensating plate 55 passes above, below, to the left and right of the compensating lens 54, and enters from the peripheral region outside the incident region of the image light ML corresponding to the compensating lens 54, i.e., from the compensating plate 55. This ensures a wide see-through field of view with respect to the outside world. The field of view range of the ambient light OL is set, for example, to about 40° upwards and about 40° downwards.

[0027] The diameter of the second lens 53 is set to 20mm to 25mm in order to ensure a wide field of view. The thickness of the first flat plate member 40 or the prism light guide member 48 in the Z direction is 6mm to 8mm, and the distance from the inner surfaces 41b, 42b of the first flat plate member 40 to the pupil position PP is approximately 12mm to 13mm. Therefore, the field of view (diagonal), which is the angle range in which the image light ML is incident on the pupil position PP, can be set to approximately 40°.

[0028] The transmissive mirror 56 is a half-mirror that reflects a portion of the image light ML that has passed through the second lens 53 and transmits a portion of the ambient light OL. The transmissive mirror 56 reflects the image light ML that has been reflected by the polarization separation film 45A of the first flat plate member 40 and passed through the quarter-wave plate 51 and the second lens 53 toward the pupil position PP. The transmissive mirror 56 is a concave mirror that covers the pupil position PP where the eye EY or pupil is located and has a concave shape toward the pupil position PP and a convex shape toward the outside world. The pupil position PP or its opening PPa is called the eye point or eye box and corresponds to the exit pupil EP of the first display unit 20a.

[0029] The transmissive mirror 56 transmits some of the ambient light OL, enabling see-through viewing of the outside world and allowing a virtual image to be superimposed on the image of the outside world. In this case, the ambient light OL passes through the first flat plate member 40 and the second flat plate member 50, but the flat plate members 40 and 50 do not produce a lens effect on the ambient light OL. The reflectivity of the transmissive mirror 56 with respect to the image light ML and ambient light OL is set to 10% to 50% within the expected incident angle range of the image light ML, from the viewpoint of ensuring the brightness of the image light ML and facilitating observation of the outside world image through see-through. The transmissive mirror 56 is formed, for example, from a dielectric multilayer film consisting of multiple dielectric layers with adjusted film thicknesses. The transmissive mirror 56 may also be a single-layer or multilayer film of a metal such as Al or Ag with adjusted film thickness. The transmissive mirror 56 is formed, for example, by lamination using vapor deposition.

[0030] In the first virtual image display device 100A, the first lens 30, the third lens 44, the second lens 53, and the transmission mirror 56 each have positive refractive power and tend to converge divergent light. The first lens 30, the third lens 44, the second lens 53, and the transmission mirror 56, along with the body of the first prism 41, the second prism 42, etc., function as an imaging optical system IS or a direct virtual image optical system DIS, similar to a single-lens microscope, that forms an erect image. In such an optical system, no intermediate images are formed in the optical path, and an image is observed in which the up, down, left, and right directions of the observed object are preserved. As a result, a real image formed on the display surface 11d of the first image forming element 11a can be formed as a virtual image projected to, for example, infinity, or a real image formed on the display surface 11d can be formed as a virtual image projected several meters away. In this case, by adjusting the refractive power of the first lens 30, the third lens 44, the second lens 53, and the transmission mirror 56, the focal length of the imaging optical system IS can be shortened to achieve the desired magnification.

[0031] Figure 3 is a conceptual perspective view of the virtual image display device 1000 according to the related technology. Figure 4 is a conceptual cross-sectional view of the virtual image display device 1000 according to the related technology shown in Figure 3. When drawing a lateral cross-sectional view of the virtual image display device 1000 according to the related technology shown in Figures 3 and 4 with respect to the YX plane passing through the optical axis AX, the same lateral cross-sectional view as in Figure 2 is obtained. As shown in Figures 3 and 4, the cross-section of the prism light guide member 48, which includes the first prism 41 and the second prism 42, with respect to the XZ plane passing through the optical axis AX of the second lens 53 included in the second flat plate member 50, is rectangular. In particular, the right side surface 48r of the prism light guide member 48, which is in contact with the inclined surface 41a into which the image light ML from the display element 11 is incident, and the outer surface 48c facing the second flat plate member 50 including the second lens 53, is parallel to the YZ plane. The outer surface 48c of the prism light guide member 48 includes the outer surface 41c of the first prism 41 and the outer surface 42c of the second prism 42. Similarly, the left side 48l of the surface of the prism light guide member 48, which is in contact with the inclined surface 41a and the outer surface 48c and faces the right side surface 48r, is also parallel to the YZ plane.

[0032] Here, the YZ plane is a hypothetical plane perpendicular to the X-axis direction, which is the direction in which the wearer's eyes (EY) are aligned.

[0033] At this time, as shown in Figure 4, unwanted light UL from the second flat plate member 50 may enter the prism light guide member 48 through the outer surface 48c, be reflected by the right side 48r or left side 48l, be emitted from the prism light guide member 48 through the inner surface 48b, and reach the eye EY as ghost or stray light through the aperture PPa at the pupil position PP. Even if the dimensions of the second flat plate member 50 and the prism light guide member 48, and the positional relationship between the second flat plate member 50 and the prism light guide member 48 with respect to the eye EY are determined so that unwanted light UL from the second flat plate member 50 does not reach the EY, the center of the eye EY on the X axis may deviate from the optical axis AX of the second lens 53. One example of this reason is when the wearer US rotates the direction of the eye EY left or right, or when the distance between the wearer US's binocular EYs is longer or shorter than the assumed interpupillary distance.

[0034] Under these conditions, a known technique involves blackening the right side 48r and / or left side 48l to reduce unwanted light originating from the image light ML, thereby absorbing light and preventing reflection. However, when blackening is applied, a portion of the external light OL that should reach the eye EY may be lost due to the blackening.

[0035] Therefore, in the virtual image display devices 100A and 100B according to one embodiment, unwanted light UL reaching the eye EY is reduced by changing the angle of the right side surface 48r and the left side surface 48l of the prism light guide member 48 with respect to the YZ plane.

[0036] Figure 5 is a conceptual perspective view of the virtual image display devices 100A and 100B according to one embodiment shown in Figure 2. Figure 6 is a conceptual cross-sectional view of the virtual image display devices 100A and 100B shown in Figures 2 and 5. As shown in Figures 5 and 6, the cross-section of the prism light guide member 48, which includes the first prism 41 and the second prism 42, in the virtual image display devices 100A and 100B, along the XZ plane passing through the optical axis AX of the second lens 53 included in the second flat plate member 50, is trapezoidal. In particular, the right side surface 48s of the prism light guide member 48, which is in contact with the inclined surface 41a into which the image light ML from the display element 11 is incident, and the outer surface 48c facing the second flat plate member 50 including the second lens 53, is not parallel to the YZ plane, but is inclined by an angle γr around a rotation axis parallel to the Y axis. The outer surface 48c of the prism light guide member 48 includes the outer surface 41c of the first prism 41 and the outer surface 42c of the second prism 42. Similarly, the left side 48m of the surface of the prism light guide member 48, which is in contact with the inclined surface 41a and the outer surface 48c and faces the right side surface 48s, is not parallel to the YZ plane but is inclined by an angle γl. For example, the absolute values ​​of angles γr and γl may be in the range of 3 to 10 degrees. For another example, the absolute values ​​of angles γr and γl may be in the range of 3 to 4 degrees. However, the direction of the axis of rotation of the inclination is not limited to the Y-axis direction.

[0037] Here, the right side surface 48s and the left side surface 48m are inclined at a constant angle with respect to the YZ plane, in a direction in which the prism light guide member 48 tapers as it moves toward the +Z axis, that is, in a direction that narrows the inner surface surface 48b of the prism light guide member 48 and / or in a direction that widens the outer surface surface 48c of the prism light guide member 48. In other words, as shown in Figures 3 and 5, when the prism light guide member 48 is viewed from the +Y direction toward the -Y direction, the right side surface 48s of the prism light guide member 48 in the virtual image display device 100A, 100B according to one embodiment (see Figure 5) is rotated clockwise by an angle γr compared to the right side surface 48r of the prism light guide member 48 in the virtual image display layer 1000 according to the related technology (see Figure 3). Similarly, as shown in Figures 3 and 5, when viewing the prism light guide member 48 from the +Y direction to the -Y direction, the left side surface 48m (see Figure 5) of the prism light guide member 48 in the virtual image display devices 100A and 100B according to one embodiment is rotated counterclockwise by an angle γl compared to the left side surface 48l (see Figure 3) of the prism light guide member 48 in the virtual image display layer 1000 according to the related technology. As a result, unwanted light UL that can reach the eye EY through the aperture PPa at pupil position PP does not include light from the second flat plate member 50 at least.

[0038] Here, the +Z axis direction is the direction from the wearer's eye EY towards the second lens 53 along the optical axis AX of the second lens 53. The YZ plane is a hypothetical plane perpendicular to the X axis direction, which is the direction in which the wearer's binocular eyes EY are aligned.

[0039] For example, the width of the prism light guide member 48 in the X-axis direction is 22 mm, and the thickness in the Z-axis direction is 6 mm. These values ​​are merely examples and do not limit this embodiment.

[0040] Referring to Figures 7, 8, 9, 10, 11, and 12, it will be explained that unwanted light UL can be reduced by tilting the right side 48s and the left side 48m with respect to the YZ plane. Figures 7, 8, and 9 are diagrams showing the results of computer simulations of the brightness distribution of image light ML and unwanted light UL observed by the eye EY when using the virtual image display device 1000 according to the related technology shown in Figures 3 and 4. Figures 10, 11, and 12 are diagrams showing the results of computer simulations of the brightness distribution of image light ML and unwanted light UL observed by the eye EY when using the virtual image display devices 100A and 100B according to one embodiment shown in Figures 5 and 6. Figures 7 and 10 show the case where the optical axis AX is at the center of the eye EY in the X direction. Figures 8 and 11 show the case where the optical axis AX is to the left of the center of the eye EY (+X direction) in the X direction. Figures 9 and 12 show the case where the optical axis AX is to the right of the center of the eye EY (-X direction) in the X direction.

[0041] Figure 7 includes graph G11, which shows the luminance distribution of the image light ML and unwanted light ULr,ULl observed in the eye EY when the virtual image display device 1000 according to related technology emits image light ML, along the horizontal (H) axis and vertical (V) axis of the eye box of the eye EY; graph G12, which shows the luminance distribution along the horizontal (H) axis; and graph G13, which shows the luminance distribution along the vertical (V) axis. In graph G11, the horizontal axis represents the horizontal (H) axis of the eye box of the eye EY, and the vertical axis represents the vertical (V) axis of the eye box. In graph G12, the horizontal axis represents the horizontal (H) axis of the eye box of the eye EY, and the vertical axis represents the ratio of the luminance of the image light ML and unwanted light ULr,ULl to the luminance of the image light ML, expressed in exponential notation. In graph G13, the vertical axis represents the vertical (V) axis of the eye box of the eye EY, and the horizontal axis represents the ratio of the brightness of the image light ML and unwanted light ULr,ULl to the brightness of the image light ML, expressed in exponential notation.

[0042] Similarly, Figure 10 includes graph G41, which shows the luminance distribution of the image light ML and unwanted light UL observed in the eye EY when a virtual image display device 100A, 100B according to one embodiment emits image light ML, along the horizontal (H) axis and vertical (V) axis of the eye box of the eye EY; graph G42, which shows the luminance distribution along the horizontal (H) axis; and graph G43, which shows the luminance distribution along the vertical (V) axis. In graph G41, the horizontal axis represents the horizontal (H) axis of the eye box of the eye EY, and the vertical axis represents the vertical (V) axis of the eye box. In graph G42, the horizontal axis represents the horizontal (H) axis of the eye box of the eye EY, and the vertical axis represents the ratio of the luminance of the image light ML and unwanted light ULr,ULl, expressed in exponential notation, with the luminance of the image light ML set to 100%. In graph G43, the vertical axis represents the vertical (V) axis of the eye box of the eye EY, and the horizontal axis represents the ratio of the brightness of the image light ML and unwanted light ULr,ULl to the brightness of the image light ML, expressed in exponential notation.

[0043] In both graphs G11, G12, and G13 in Figure 7 and graphs G41, G42, and G43 in Figure 10, when the optical axis AX strikes the center of the eye EY, the brightness of unwanted light ULr and ULL is sufficiently low compared to the brightness of the image light ML. Furthermore, the area of ​​the eye box of the eye EY occupied by unwanted light ULr and ULL is sufficiently far from the area occupied by the image light ML, and is also sufficiently narrow compared to the area occupied by the image light ML. Moreover, in Figure 10, the unwanted light ULr and ULL is further reduced compared to the case in Figure 7.

[0044] Figure 8 includes graph G21, which shows the luminance distribution of the image light ML and unwanted light ULr,ULl observed in the eye EY when the virtual image display device 1000 according to related technology emits image light ML, along the horizontal (H) axis and vertical (V) axis of the eye box of the eye EY; graph G22, which shows the luminance distribution along the horizontal (H) axis; and graph G23, which shows the luminance distribution along the vertical (V) axis. In graph G21, the horizontal axis represents the horizontal (H) axis of the eye box of the eye EY, and the vertical axis represents the vertical (V) axis of the eye box. In graph G22, the horizontal axis represents the horizontal (H) axis of the eye box of the eye EY, and the vertical axis represents the ratio of the luminance of the image light ML and unwanted light ULr,ULl to the luminance of the image light ML, expressed in exponential notation. In graph G23, the vertical axis represents the vertical (V) axis of the eye box of the eye EY, and the horizontal axis represents the ratio of the brightness of the image light ML and unwanted light ULr,ULl, expressed exponentially, with the brightness of the image light ML set to 100%.

[0045] Similarly, Figure 11 includes graph G51, which shows the luminance distribution of the image light ML and unwanted light UL observed in the eye EY when the virtual image display devices 100A and 100B according to one embodiment emit the image light ML, along the horizontal (H) axis and vertical (V) axis of the eye box of the eye EY; graph G52, which shows the luminance distribution along the horizontal (H) axis; and graph G53, which shows the luminance distribution along the vertical (V) axis. In graph G51, the horizontal axis represents the horizontal (H) axis of the eye box of the eye EY, and the vertical axis represents the vertical (V) axis of the eye box. In graph G52, the horizontal axis represents the horizontal (H) axis of the eye box of the eye EY, and the vertical axis represents the ratio of the luminance of the image light ML and unwanted light ULr,ULl, expressed in exponential notation, with the luminance of the image light ML set to 100%. In graph G53, the vertical axis represents the vertical (V) axis of the eye box of the eye EY, and the horizontal axis represents the ratio of the brightness of the image light ML and unwanted light ULr,ULl, expressed exponentially, with the brightness of the image light ML set to 100%.

[0046] As shown in graphs G21 and G22 of Figure 8, when a virtual image display device 1000 using related technology emits image light ML, and the optical axis AX strikes the left side of the center of the eye EY in the X direction (+X direction), a non-negligible unwanted light ULr may be observed on the right side of the eye box of the eye EY (+H direction, -X direction). As an example of the results of the computer simulation shown in Figure 8, the brightness of the unwanted light ULr was approximately 5.3% of the brightness of the image light ML. On the other hand, by tilting the right side surface 48r of the prism light guide member 48 of the virtual image display device 1000 according to the related technology shown in Figures 3 and 4 to form the right side surface 48s of the virtual image display devices 100A and 100B according to one embodiment shown in Figures 5 and 6, that is, when the virtual image display devices 100A and 100B according to one embodiment emit image light ML and the optical axis AX strikes the left side of the center of the eye EY in the X direction (+X direction), the unwanted light ULr observed on the right side of the eye box of the eye EY (+H direction, -X direction), as shown in graphs G51 and G52 in Figure 11, is dramatically reduced compared to the case in Figure 8. As an example of the results of the computer simulation shown in Figure 11, the brightness of the unwanted light ULr was approximately 0.1% of the brightness of the image light ML.

[0047] Figure 9 includes graph G31, which shows the luminance distribution of the image light ML and unwanted light ULr,ULl observed in the eye EY when the virtual image display device 1000 according to related technology emits image light ML, along the horizontal (H) axis and vertical (V) axis of the eye box of the eye EY; graph G32, which shows the luminance distribution along the horizontal (H) axis; and graph G33, which shows the luminance distribution along the vertical (V) axis. In graph G31, the horizontal axis represents the horizontal (H) axis of the eye box of the eye EY, and the vertical axis represents the vertical (V) axis of the eye box. In graph G32, the horizontal axis represents the horizontal (H) axis of the eye box of the eye EY, and the vertical axis represents the ratio of the luminance of the image light ML and unwanted light ULr,ULl to the luminance of the image light ML, expressed in exponential notation. In graph G33, the vertical axis represents the vertical (V) axis of the eye box of the eye EY, and the horizontal axis represents the ratio of the brightness of the image light ML and unwanted light ULr,ULl, expressed exponentially, with the brightness of the image light ML set to 100%.

[0048] Similarly, Figure 12 includes graph G61, which shows the luminance distribution of the image light ML and unwanted light UL observed in the eye EY when the virtual image display devices 100A and 100B according to one embodiment emit the image light ML, along the horizontal (H) axis and vertical (V) axis of the eye box of the eye EY; graph G62, which shows the luminance distribution along the horizontal (H) axis; and graph G63, which shows the luminance distribution along the vertical (V) axis. In graph G61, the horizontal axis represents the horizontal (H) axis of the eye box of the eye EY, and the vertical axis represents the vertical (V) axis of the eye box. In graph G62, the horizontal axis represents the horizontal (H) axis of the eye box of the eye EY, and the vertical axis represents the ratio of the luminance of the image light ML and unwanted light ULr,ULl, expressed in exponential notation, with the luminance of the image light ML set to 100%. In graph G63, the vertical axis represents the vertical (V) axis of the eye box of the eye EY, and the horizontal axis represents the ratio of the brightness of the image light ML and unwanted light ULr,ULl, expressed in exponential notation, with the brightness of the image light ML set to 100%.

[0049] As shown in graphs G31 and G32 of Figure 9, when a virtual image display device 1000 using related technology emits image light ML, and the optical axis AX strikes the right side of the center of the eye EY in the X direction (-X direction), a non-negligible unwanted light ULl may be observed on the left side of the eye box of the eye EY (-H direction, +X direction). As an example of the results of the computer simulation shown in Figure 9, the brightness of the unwanted light ULl was approximately 5.3% of the brightness of the image light ML. On the other hand, by tilting the left side surface 48l of the prism light guide member 48 of the virtual image display device 1000 according to the related technology shown in Figures 3 and 4 to form the left side surface 48m of the virtual image display devices 100A and 100B according to one embodiment shown in Figures 5 and 6, that is, as shown in graphs G61 and G62 in Figure 12, when the virtual image display devices 100A and 100B according to one embodiment emit image light ML and the optical axis AX strikes to the right of the center of the eye EY in the X direction (-X direction), the unwanted light ULr observed on the left side of the eye box of the eye EY (-H direction, +X direction) is dramatically reduced compared to the case in Figure 9. As an example of the results of the computer simulation shown in Figure 12, the brightness of the unwanted light ULr was approximately 0.1% of the brightness of the image light ML.

[0050] The first embodiment of the virtual image display device 100A, 100B, or optical unit 100 described above is a direct virtual image type virtual image display device 100A, 100B, or optical unit 100, comprising: a display element 11 that emits image light ML; a first prism 41 into which the image light ML from the display element 11 is incident; a second prism 42 joined to the first prism 41 to form a parallel plate-shaped prism light guide member 48; a semi-transparent reflective film 45 provided at the joint between the first prism 41 and the second prism 42 and reflecting the image light ML guided in the first prism 41; a second lens 53 as a plano-convex first lens positioned opposite the outer surface 41c of the first prism 41 into which the image light ML reflected by the semi-transparent reflective film 45 is incident; and a first lens The prism light guide member 48 comprises a transmissive mirror 56 formed on the convex surface of the second lens 53 and reflecting a portion of the image light ML reflected by the semi-transmissive reflective film 45 toward the semi-transmissive reflective film 45, and a quarter-wave plate 51 positioned between the outer surface 41c of the first prism 41 and the second lens 53 as the first lens, with an air gap in between, and of the surface of the prism light guide member 48, the right side surface 48s, 41s, 42s or the left side surface 48m, 41m, 42m, which are in contact with the inclined surface 41a as the first surface into which the image light ML from the display element 11 is incident, and the outer surfaces 48c, 41c, 42c as the second surface facing the second lens 53 as the first lens, are inclined with respect to a virtual first plane perpendicular to the first direction in which the wearer's binoculars EX are aligned.

[0051] According to the first embodiment of the virtual image display device 100A, 100B or optical unit 100, unwanted light ULr,ULl reaching the eyes EY can be reduced by tilting the right side 48s and left side 48m of the prism light guide member 48 with respect to the YZ plane perpendicular to the X-axis direction in which the wearer's eyes EX are aligned, without using black coating which may cause a loss of external light OL. This tilt may be applied in a rotational direction about the Y-axis direction which is perpendicular to the Z-axis direction which is the front-to-back direction as seen from the wearer US, and the X-axis direction which is the direction in which the wearer's eyes EY are aligned.

[0052] [Second Embodiment] In the first embodiment described above, as shown in Figures 5 and 6, a configuration was described in which unwanted light ULr,ULl reaching the eye EY is reduced by inclining the right side 48s and left side 48m of the prism light guide member 48 with respect to the YZ plane. In the second embodiment, a configuration will be described in which assembly contact surfaces for accurately fixing the virtual image display devices 100A and 100B to external parts such as lens barrels are provided on the right side 48s and left side 48m of the prism light guide member 48 while reducing unwanted light ULr,ULl reaching the eye EY. The assembly contact surface includes at least one of a contact surface and a reference surface. The contact surface is provided to contact the external part in order to fix the prism light guide member 48 to the external part. The reference surface has a shape complementary to the external part in order to adjust its position and orientation relative to the external part.

[0053] Figure 13 is a conceptual perspective view of the virtual image display devices 100A and 100B according to the second embodiment. Figure 14 is a conceptual cross-sectional view of the virtual image display devices 100A and 100B shown in Figure 13. The virtual image display devices 100A and 100B shown in Figures 13 and 14 are obtained by making the following changes to the virtual image display devices 100A and 100B according to the first embodiment shown in Figures 5 and 6. Specifically, an assembly contact surface 48t parallel to the YZ plane is provided on a part of the right side surface 48s of the prism light guide member 48 shown in Figures 5 and 6. In addition, an assembly contact surface 48n parallel to the YZ plane is provided on a part of the left side surface 48m of the prism light guide member 48 shown in Figures 5 and 6.

[0054] Furthermore, since the right side surface 48s of the prism light guide member 48 includes the right side surface 41s of the first prism 41 and the right side surface 42s of the second prism 42, depending on the position of the assembly contact surface 48t, the assembly contact surface 41t may be provided as part of the assembly contact surface 48t on the right side surface 41s of the first prism 41, or the assembly contact surface 42t may be provided as part of the assembly contact surface 48t on the right side surface 42s of the second prism 42. Similarly, since the left side surface 48m of the prism light guide member 48 includes the left side surface 41m of the first prism 41 and the left side surface 42m of the second prism 42, depending on the position of the assembly contact surface 48n, the assembly contact surface 41n may be provided as part of the assembly contact surface 48n on the left side surface 41m of the first prism 41, or the assembly contact surface 42n may be provided as part of the assembly contact surface 48n on the left side surface 42m of the second prism 42.

[0055] The virtual image display device 100A, 100B, or optical unit 100 of the second embodiment described above has a right side surface 48s and a left side surface 48m that are inclined with respect to the YZ plane, and assembly contact surfaces 48t and 48n that have surfaces parallel to the YZ plane. Therefore, the virtual image display device 100A, 100B, or optical unit 100 can be accurately fixed to external parts such as a lens barrel while reducing unwanted light ULr and ULl that reach the eye EY.

[0056] A specific embodiment of the virtual image display device is a direct virtual image type virtual image display device comprising: a display element that emits image light; a first prism into which the image light from the display element is incident; a second prism joined to the first prism to form a parallel plate-shaped prism light guide member; a semi-transparent reflective film provided at the joint between the first prism and the second prism and reflecting the image light guided in the first prism; a plano-convex first lens positioned opposite the outer surface of the first prism into which the image light reflected by the semi-transparent reflective film is incident; and a convex surface formed on the first lens that reflects the image light reflected by the semi-transparent reflective film. The prism light guide member comprises a transmissive mirror that reflects a portion of the incoming image light toward a semi-transparent reflective film, and a quarter-wave plate positioned between the outer surface of the first prism and the first lens with an air gap in between. The third surface of the prism light guide member, which is in contact with the first surface onto which the image light from the display element is incident and the second surface facing the first lens, is inclined at a certain angle with respect to a virtual first plane perpendicular to the first direction in which the eyes of the wearer wearing the virtual image display device are aligned, in a direction in which the prism light guide member tapers as it moves from the wearer's eyes toward the first lens along the optical axis of the first lens.

[0057] In a specific embodiment of the virtual image display device, the third surface is inclined in a rotational direction about a rotation axis parallel to a third direction that is perpendicular to the first direction and a second direction parallel to the wearer's front-to-back direction.

[0058] In a specific embodiment of a virtual image display device, the fourth surface of the prism light guide member, which is in contact with the first and second surfaces and faces the third surface, is inclined with respect to the first plane, and the prism light guide member includes a fifth surface that faces the second surface and is in contact with the first, third, and fourth surfaces, and the third and fourth surfaces are each inclined with respect to the first plane in a direction that narrows the fifth surface and / or widens the second surface.

[0059] In a specific embodiment of a virtual image display device, the angle of the third surface and / or the fourth surface with respect to the first surface is within the range of 3 to 10 degrees.

[0060] In a specific embodiment of a virtual image display device, the angle of the third surface and / or the fourth surface with respect to the first surface is within the range of 3 to 4 degrees.

[0061] In the above-described virtual image display device, unwanted light reaching the eyes can be reduced by tilting the right and / or left sides of the prism light guide member with respect to a plane perpendicular to the direction in which the wearer's eyes are aligned.

[0062] In a specific embodiment, the virtual image display device further comprises an assembly contact surface that is in contact with the third surface and includes a sixth surface parallel to the first plane, the assembly contact surface including at least one of a contact surface provided to contact the external part in order to fix the prism light guide member to the external part, and a reference surface having a shape complementary to the external part in order to adjust the position and orientation of the prism light guide member with respect to the external part.

[0063] The above-described virtual image display device has a right side and / or left side that are inclined with respect to a plane perpendicular to the direction in which the wearer's eyes are aligned, and an assembly contact surface having a surface parallel to said plane. Therefore, the virtual image display device can be precisely fixed to external parts such as a lens barrel while reducing unwanted light reaching the eyes.

[0064] In a specific embodiment of a virtual image display device, the first surface is equipped with a second lens into which image light from a display element is incident, the semi-transparent reflective film is equipped with a polarization-separating film that reflects the image light according to the polarization direction, the second lens, prism light guide member, polarization-separating film, first lens, transmission mirror, and quarter-wave plate constitute a single-lens microscope type imaging optical system that forms an erect image, and the first prism internally reflects the image light twice while diverging it.

[0065] In a specific embodiment of a virtual image display device, the polarization separation film reflects the first portion of the image light arriving from the first prism that is s-polarized, and transmits the first portion that has become p-polarized after being reflected by a transmission mirror and passing through the first quarter-wave plate.

[0066] In a specific embodiment of a virtual image display device, the polarization separation film reflects the first portion of the image light arriving from the first prism that is s-polarized, and transmits the first portion that has become p-polarized after being reflected by a transmission mirror and passing through the first quarter-wave plate.

[0067] In a specific embodiment, the virtual image display device further comprises a compensating lens having a concave surface bonded to the convex surface of the first lens via a transmissive mirror, and a surface parallel to the outer surface of the first prism.

[0068] In a specific embodiment, the virtual image display device further comprises a compensating plate provided around the compensating lens and extending parallel to the prism light guide member.

[0069] In the above virtual image display device, the distance from the display element to the transmission mirror can be easily shortened, the prism light guide member can be miniaturized, and the display element and the first lens can also be easily miniaturized.

[0070] In a specific embodiment, the optical unit is a direct virtual image type virtual image display device comprising: a display element that emits image light; a first prism into which the image light from the display element is incident; a second prism joined to the first prism to form a parallel plate-shaped prism light guide member; a semi-transparent reflective film provided at the joint between the first prism and the second prism and reflecting the image light guided in the first prism; a plano-convex first lens positioned opposite the outer surface of the first prism into which the image light reflected by the semi-transparent reflective film is incident; and a convex surface formed on the first lens and reflected by the semi-transparent reflective film. The optical unit comprises a transmissive mirror that reflects a portion of the incoming image light toward a semi-transparent reflective film, and a quarter-wave plate positioned between the outer surface of the first prism and the first lens with an air gap in between. The third surface of the prism light guide member, which is in contact with the first surface onto which the image light from the display element is incident and the second surface facing the first lens, is inclined at a certain angle with respect to a virtual first plane perpendicular to the first direction in which the eyes of the wearer wearing the optical unit are aligned, in a direction in which the prism light guide member tapers as it moves from the wearer's eyes toward the first lens along the optical axis of the first lens.

[0071] In the above-described virtual image display device, unwanted light reaching the eyes can be reduced by tilting the right and / or left sides of the prism light guide member with respect to a plane perpendicular to the direction in which the wearer's eyes are aligned. [Explanation of symbols]

[0072] 11…Display element, 11a,11b…Image forming element, 11d…Display surface, 20a,20b…Display section, 30…First lens, 30f…Light incident surface, 30g…Light emission surface, 31…Parallel plate, 32…Lens section, 40…First flat plate-shaped member, 40w…Lower plane, 41…First prism, 41a,41d…Inclined surface, 41b…Inner surface, 41c…Outer surface, 41l,41m…Left side, 41n…Assembly contact surface, 41r,41s…Right side, 41t…Assembly contact surface, 42…Second prism, 42b…Inner surface, 42c…Outer surface, 42d…Inclined surface, 42 l, 42m…left side, 42n…assembly contact surface, 42r, 42s…right side, 42t…assembly contact surface, 42w…bottom plane, 44…third lens, 44a…incident optical surface, 44b…inclined surface, 45…semitransmissive reflective film, 45A…polarization separation film, 48…prism light guide member, 48b…inner side, 48c…outer side, 48l, 48m…left side, 48n…, 48r, 48s…right side, 48t…, 50…second flat plate member, 50c…inner side, 51…quarter wave plate, 52…cover member, 53…second lens, 53f…plane, 53g…convex surface, 54… Compensation lens, 54f...concave, 54g...flat, 55...compensation plate, 55f, 55g...flat, 56...transmission mirror, 58...optical element, 61...spacer, 71...case, 80a, 80b...circuit component, 90...user terminal, 100...optical unit, 100A, 100B...virtual image display device, 100C...support device, 102a, 102b...display drive unit, 103a, 103b...combiner, 200...head-mounted virtual image display device, head-mounted display, HMD, 1000...virtual image display device, AX...optical axis, c...circular polarization, C R1…First light-gathering reflector, CT…Adhesive, DIS…Direct virtual image optical system, EP…Exit pupil, EY…Eye, Binoculars, G11, G12, G13, G21, G22, G23, G31, G32, G33, G41, G42, G43, G51, G52, G53, G61, G62, G63…Graph, ML…Image light, OL…Outside light, p…p-polarization, PP…Pupil position, PPa…Aperture, s…s-polarization, SP…Gap, UL, ULL, ULR…Unwanted light, US…Wearer, β0…Reflection angle, βmax…Maximum reflection angle, γl, γr…Angle, θ…Inclination angle

Claims

1. A direct virtual image type virtual image display device, A display element that emits image light, A first prism into which the image light from the display element is incident, A second prism is joined to the first prism to form a parallel plate-shaped prism light guide member, A semi-transparent reflective film is provided at the junction of the first prism and the second prism, and reflects the image light guided in the first prism, A plano-convex first lens is positioned opposite the outer surface of the first prism to which the image light reflected by the semi-transparent reflective film is incident, A transmissive mirror formed on the convex surface of the first lens, which reflects a portion of the image light reflected by the semi-transparent reflective film toward the semi-transparent reflective film, A quarter-wave plate is placed between the outer surface of the first prism and the first lens, with an air gap in between. Equipped with, Of the surfaces of the prism light guide member, the third surface that contacts the first surface onto which the image light from the display element is incident and the second surface facing the first lens is inclined at a certain angle with respect to a virtual first plane perpendicular to the first direction in which the eyes of the wearer wearing the virtual image display device are aligned, in a direction in which the prism light guide member tapers as it moves from the wearer's eyes toward the first lens along the optical axis of the first lens. Virtual image display device.

2. The third surface is inclined in a rotational direction about a rotation axis parallel to a third direction that is perpendicular to the first direction and a second direction parallel to the wearer's front-to-back direction. The virtual image display device according to claim 1.

3. Of the surfaces of the prism light guide member, the fourth surface that is in contact with the first surface and the second surface and faces the third surface is inclined with respect to the first plane. The prism light guide member has a fifth surface that faces the second surface and is in contact with the first surface, the third surface and the fourth surface, The third surface and the fourth surface are each inclined with respect to the first plane in a direction that narrows the fifth surface and / or widens the second surface. The virtual image display device according to claim 1.

4. The angle of the third surface and / or the fourth surface with respect to the first surface is within the range of 3 to 10 degrees. The virtual image display device according to claim 3.

5. The angle of the third surface and / or the fourth surface with respect to the first surface is within the range of 3 to 4 degrees. The virtual image display device according to claim 3.

6. The assembly surface further includes a sixth surface that is in contact with the third surface and parallel to the first plane, The aforementioned assembly contact surface is A contact surface is provided to contact the external part in order to fix the prism light guide member to the external part, A reference surface having a shape complementary to the external part in order to adjust the position and orientation of the prism light guide member with respect to the external part, Including at least one of the following: The virtual image display device according to claim 1.

7. The first surface includes a second lens into which the image light from the display element is incident, The semi-transparent reflective film comprises a polarization separation film that reflects the image light according to its polarization direction, The second lens, the prism light guide member, the polarization separation film, the first lens, the transmission mirror, and the quarter-wave plate constitute a single-lens microscope type imaging optical system that forms an erect image. The first prism internally reflects the image light twice while diverging it. The virtual image display device according to claim 1.

8. The polarization separation film reflects the first portion of the image light arriving from the first prism that is s-polarized, and transmits the first portion that has become p-polarized by being reflected by the transmission mirror and returning after passing through the quarter-wave plate. The virtual image display device according to claim 7.

9. The compensating lens further comprises a concave surface joined to the convex surface of the first lens via the transmissive mirror, and a surface parallel to the outer surface of the first prism. The virtual image display device according to claim 1.

10. The compensating lens is further provided with a compensating plate that extends parallel to the prism light guide member and is located around the compensating lens. The virtual image display device according to claim 9.

11. A direct virtual image type optical unit, A display element that emits image light, A first prism into which the image light from the display element is incident, A second prism is joined to the first prism to form a parallel plate-shaped prism light guide member, A semi-transparent reflective film is provided at the junction of the first prism and the second prism, and reflects the image light guided in the first prism, A plano-convex first lens is positioned opposite the outer surface of the first prism to which the image light reflected by the semi-transparent reflective film is incident, A transmissive mirror formed on the convex surface of the first lens, which reflects a portion of the image light reflected by the semi-transparent reflective film toward the semi-transparent reflective film, A quarter-wave plate is placed between the outer surface of the first prism and the first lens, with an air gap in between. Equipped with, Of the surfaces of the prism light guide member, the third surface that contacts the first surface onto which the image light from the display element is incident and the second surface facing the first lens is inclined at a certain angle with respect to a virtual first plane perpendicular to the first direction in which the eyes of the wearer wearing the optical unit are aligned, in a direction in which the prism light guide member tapers as it moves from the wearer's eyes toward the first lens along the optical axis of the first lens. Optical unit.

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